Chemical profiling, bio-guided purification, and cytotoxic effect of two African spices: Hypodaphnis zenkeri Engl. Stapf (Lauraceae) and Staudtia kamerunensis warb (Myristicaceae) on human prostate cancer cell lines.

ETHNOPHARMACOLOGICAL RELEVANCE: Prostate cancer remains a significant burden in low- and middle-income countries and the second leading cause of death around the world. Spices used in daily cuisine contain interesting phytochemical components capable of helping prevent and cure cancer. AIM: This study aims to give sufficient phytochemical information on two understudied species, Staudtia kamerunensis Warb. (Myristicaceae) and Hypodaphnis zenkeri Engl. Stapf. (Lauraceae), and to study their cytotoxicity against prostate cancer cells in its early form and when they have developed metastasis. MATERIALS AND METHODS: To reach this goal, normal procedures for phytochemical analysis were followed; these include collection, drying, crushing and extraction of plant materials using organic solvents. GC-MS (Gas chromatography- Mass Spectrometry) was used to evaluate the volatile phytochemicals contained in the extracts, and open-column chromatography was used to isolate the pure compounds used in this study. A bio-guided exploration of Hypodaphnis zenkeri (Lauraceae) (leaves, seeds, stems) guided us in selecting the extract for further analysis. An established MTT assay was used to measure cell proliferation. Three prostate cancer cell lines were considered in this study, DU145 and PC3, human androgens-independent prostate carcinoma cells and LNCaP, which are cells derived from metastasis of a human prostate and respond to androgens, oestrogens and progestins. The eight compounds isolated were characterized using HREIMS, 1D and 2D NMR. RESULTS: Among the three extracts from Hypodaphnis zenkeri, considered for biological testing, the leaf extract displayed better activities with a CC50 of 180 µg/mL against DU 145 cells, 184 µg/mL against PC3 cells and 194 µg/mL against LNCaP cells. These results were justified when GC-MS analysis of the different extracts was performed. Fifty compounds were identified from the leaves, representing 96.06% of the volatile components, with most displaying anticancer activities or activities against vectors favorizing cancer growth (inflammation, etc.). An attempt to isolate the active principle responsible for the cancer activity led to the isolation of five pure compounds, namely Eicosane [1], Nonacos-1-ene [2], Palmitic acid [3], Glucoside Stigmasterol [4] and Butane-1,2,3,4-tetraol [5]. Eicosane was identified as being responsible in part for the observed activity, even though it exhibited weak cytotoxicity with the lowest CC50 equal to 30 µg/mL against DU 145 cells. Staudtia kamerunensis sap was investigated in our previous studies with the isolation of Oleanan-12-ene-2α,3ß -diol [6] and 2α, 3ß -dihydroxylup-20-ene [7] among the major components, with significant antibacterial properties. Oleanan-12-ene-2α,3ß -diol [7] in this study displayed a CC50 of 20 µg/mL against DU145 cells, 22 µg/mL against PC3 cells, 18 µg/mL against LNCaP cells, and 32 µg/mL in HMEC affording a selectivity index >2. Contrary to what was observed in our previous study, the activity of Oleanan-12-ene-2α,3ß -diol was lost in the presence of 2α, 3ß -dihydroxylup-20-ene. CONCLUSION: the cytotoxic effect of extract from Staudtia and Hypodaphnis genera and pure isolates are here reported for the first time, as well as the pure isolates. These studies exhibit the cytotoxic potential of two traditional African spices and, more specifically, Oleanan-12-ene-2α,3ß -diol and eicosane, isolated from these plant species.

Occurrence, Serotypes and Virulence Characteristics of Shiga-Toxin-Producing Escherichia coli Isolates from Goats on Communal Rangeland in South Africa.

Shiga-toxin-producing Escherichia coli is a foodborne pathogen commonly associated with human disease characterized by mild or bloody diarrhea hemorrhagic colitis and hemolytic uremic syndrome. This study investigated the occurrence of STEC in fecal samples of 289 goats in South Africa using microbiological culture and PCR. Furthermore, 628 goat STEC isolates were characterized by serotype (O:H) and major virulence factors by PCR. STEC was found in 80.2% (232/289) of goat fecal samples. Serotyping of 628 STEC isolates revealed 63 distinct serotypes including four of the major top seven STEC serogroups which were detected in 12.1% (35/289) of goats: O157:H7, 2.7% (8/289); O157:H8, 0.3%, (1/289); O157:H29, 0.3% (1/289); O103:H8, 7.6% (22/289); O103:H56, 0.3% (1/289); O26:H2, 0.3% (1/289); O111:H8, 0.3% (1/289) and 59 non-O157 STEC serotypes. Twenty-four of the sixty-three serotypes were previously associated with human disease. Virulence genes were distributed as follows: stx1, 60.6% (381/628); stx2, 72.7% (457/628); eaeA, 22.1% (139/628) and hlyA, 78.0% (490/628). Both stx1 and stx2 were found in 33.4% (210/628) of isolates. In conclusion, goats in South Africa are a reservoir and potential source of diverse STEC serotypes that are potentially virulent for humans. Further molecular characterization will be needed to fully assess the virulence potential of goat STEC isolates and their capacity to cause disease in humans.

Synthesis, Antibacterial, and Cytotoxicity Evaluation of Oleanolic Acid-4-aminoquinoline Based Hybrid Compounds.

AIM: The study aims to prepare a class of oleanolic-based compounds. BACKGROUND: Conventional drugs used to treat infectious diseases suffer from limitations such as drug toxicity and drug resistance. The resistance of microbes to antimicrobial agents is a significant challenge in treating microbial infections. Combining two or more drugs with different modes of action to treat microbial infections results in a delay in developing drug resistance by the microbes. However, it is challenging to select the appropriate drugs for combination therapy due to the differences in stability and pharmacokinetic profile of the drugs. Therefore, developing hybrid compounds using the existing drugs is a promising approach to design effective antimicrobial agents. OBJECTIVES: To prepare oleanolic-based hybrid compounds followed by characterization, in vitro antibacterial and cytotoxicity evaluation. METHODS: Oleanolic acid-4-aminoquinoline-based hybrid compounds were synthesized via esterification and amidation. The compounds were characterized using FTIR, NMR, and UHPLC-HRMS. Oleanolic acid (OA) was isolated from the flower buds of Syzygium aromaticum (L.) Merr. & L.M.Perry, a species from Kingdom Plantae, order Mytales in the Myrtaceae family. Antibacterial activity was determined against selected strains of bacteria using the microdilution assay and cytotoxicity activity was assessed using the sulforhodamine B assay against selected cancer cell lines. RESULTS: The synthesized hybrid compounds exhibited antibacterial activity against the Gram-positive bacteria Enterococcus faecalis (ATCC13047), Bacillus subtilis (ATCC19659), Staphylococcus aureus as well as Gram-negative bacteria, Klebsiella oxytoca (ATCC8724), Escherischia coli (ATCC25922), and Proteus vulgaris (ATCC6380) with minimum inhibitory concentrations of 1.25 mg/mL compared to oleanolic acid (2.5 mg/mL). Compounds 13 and 14 displayed cytotoxicity in vitro against the cancer cell lines (MCF-7 and DU 145) compared to the oleanolic acid (IC50 ˃ 200 µM). CONCLUSION: Modification of C28 of OA enhanced its biological activity.